/*
 * Copyright 2013-2023 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.alibaba.cloud.nacos.refresh;

import java.util.Iterator;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * @author: ruansheng
 * @date: 2024-01-22
 */
public final class NacosSnapshotConfigManager {

    private NacosSnapshotConfigManager() {
    }

    private static final Logger log = LoggerFactory.getLogger(NacosSnapshotConfigManager.class);

    private static final Map<String, String> CONFIG_INFO_SNAPSHOT_MAP = new ConcurrentHashMap<>(8);

    private static final int MAX_SNAPSHOT_COUNT = 100;

    private static String formatConfigSnapshotKey(String dataId,
                                                  String group) {
        return dataId + "@" + group;
    }

    public static String getAndRemoveConfigSnapshot(String dataId,
                                                    String group) {
        String configInfo = CONFIG_INFO_SNAPSHOT_MAP.get(formatConfigSnapshotKey(dataId, group));
        removeConfigSnapshot(dataId, group);
        return configInfo;
    }

    public static void putConfigSnapshot(String dataId,
                                         String group,
                                         String configInfo) {
        try {
            // Theoretically, the capacity limit restriction will never be triggered.
            // This portion of the code serves as an additional fault tolerance layer.
            if (CONFIG_INFO_SNAPSHOT_MAP.size() > MAX_SNAPSHOT_COUNT) {
                Iterator<Map.Entry<String, String>> iterator = CONFIG_INFO_SNAPSHOT_MAP.entrySet().iterator();
                iterator.next();
                iterator.remove();
            }
            String snapshotKey = formatConfigSnapshotKey(dataId, group);
            if (configInfo == null) {
                CONFIG_INFO_SNAPSHOT_MAP.remove(snapshotKey);
            } else {
                CONFIG_INFO_SNAPSHOT_MAP.put(snapshotKey, configInfo);
            }
        } catch (Exception e) {
            log.warn("remove nacos config snapshot error", e);
        }
    }

    public static void removeConfigSnapshot(String dataId,
                                            String group) {
        CONFIG_INFO_SNAPSHOT_MAP.remove(formatConfigSnapshotKey(dataId, group));
    }

}
